Bioenergy feedstocks offset demand for conventional petroleum-based energy resources. Switchgrass (Panicum virgatum L.) is a warm-season perennial grass that has been utilized for lingo-cellulosic ethanol production and direct energy via combustion. However, little is known about its potential as a feedstock in the semi-arid northern Great Plains USA, including effects of N fertilizer application on system productivity and environmental quality. A field study initiated in 2009 seeded ‘Sunburst’ switchgrass into plots with fertilizer N broadcast each spring at 0, 28, 56, and 84 kg N per ha as urea, with four treatment replicates. Each fall beginning in 2011, aboveground biomass was harvested, weighed, and dried. Soil cores to a depth of 1.2 m were taken in fall 2018, air-dried, and analyzed for soil nitrate. Switchgrass biomass ranged from 1.8 to 12.3 Mg per ha. In most years, N application increased switchgrass biomass, but response to N rates above 28 kg per ha was inconsistent. Biomass from fertilized switchgrass averaged 6.5 Mg per ha compared to 4.4 Mg per ha for the unfertilized control.  Soil nitrate levels indicated the potential of over-fertilization of switchgrass feedstocks to negatively impact water resources in drylands. 

How to cite: Allen, B., Sainju, U., and Dangi, S.: Optimized fertilizer N rates for bioenergy feedstock production and water quality in drylands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20790, https://doi.org/10.5194/egusphere-egu24-20790, 2024.

Volcanic tuffs containing high percentage of zeolites have been extensively studied, both in their natural state  or enriched with nitrogen, as a means of enhancing soil properties and fertilizer efficiency. Limited data however exist on their application in acidic sandy soils and in conjunction with organic fertilizers.

This work consists of a 50-day laboratory incubation study wherein the nitrogen dynamics in an acidic sandy-loam agricultural soil fertilized with various nitrogen sources were investigated. These sources included urea, nitrogen-enriched chabazite zeolite tuff, and pelleted composted manure. Additionally, the nitrogen sources were tested in combination with the addition of chabazite zeolite tuff in its natural state to act as a soil improver.

The results revealed distinct behaviors among the various nitrogen sources, particularly affecting soil pH and nitrogen dynamics. Mineralization was very slow in manure-fertilized soil, whereas nitrogen-enriched zeolite exhibited a more balanced behavior in terms of net nitrate production and ammonium consumption. Nitrogen-enriched zeolite and urea demonstrated a temporary "liming" effect, while pelleted manure promoted a prolonged shift of soil pH toward neutral values.

In conclusion, nitrogen-charged chabazite zeolite tuff proved to be a valuable nitrogen source in acidic sandy-loam soil, serving as a viable alternative to synthetic fertilizers and an effective means of nitrogen recycling.

How to cite: Alberghini, M., Ferretti, G., Galamini, G., Faccini, B., Balzan, S., and Coltorti, M.: Assessment of Nitrogen Dynamics in an Acidic Sandy-Loam Soil: Impact of Varied Nitrogen Sources and Incorporation of Chabazite Zeolite Tuff, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11211, https://doi.org/10.5194/egusphere-egu24-11211, 2024.

 Jordan faces a critical challenge of land degradation and water scarcity, primarily affecting the extensive natural rangeland (Badia), which covers over 80% of the country's area. The degradation of natural vegetation, adversely affects local agropastoral communities that are depending on livestock farming and triggeing downstream issues such as flash floods and sedimentation in dams. Water harvesting and increasing vegetation cover are promising technologies to adapt and reduce the impact.

  The Badia Research Site (BRS), a confined watershed of approximately 1000 hectares, rainwater harvesting (RWH) and plantation techniques have shown promise in reducing soil erosion and runoff rates and enhancing various ecosystem services. The BRS research is mainly led by the International Center for Agricultural Research in the Dry Areas (ICARDA) and the Jordan National Agriculture Research Center (NARC), supported by the United States Forestry Service (USFS).

  This study involves (1) scaling out two RWH techniques, namely the Vallerani and the Marab, on a larger basin. The scaling out utilises local and international datasets, incorporating biophysical parameters such as land use, digital elevation models, slope, topographic wetness index, soil texture, and climate data. Optimal ecological conditions for plants, including temperature and soil pH, are considered. (2) The Soil and Water Assessment Tool (SWAT) is employed to analyse and assess the impact on surface hydrological processes.

  The focus is on the Wadi Al Mujib basin, covering 6584.37 km² in the central part of Jordan. The semi-arid to arid environment comprises two principal wadies, Wadi Al Walah and Wadi Mujib, with distinct catchment surfaces. The basin's predominantly desert land, receiving varying levels of rainfall, poses challenges to 80% of its area, while the remaining 20% is dedicated to agricultural and residential use.

  The study further employs the model to evaluate global climate change scenarios, assessing the impact and quantifying changes in ecosystem services with and without restoration efforts. These findings contribute to supporting the Jordanian government's restoration endeavours, offering a holistic approach to addressing land degradation and water scarcity challenges in the region.

Keywords: Watershed assessment, Degraded land restoration, Suitability mapping, Water harvesting techniques, Sustainable land management, and Ecosystem Services

How to cite: Haddad, M., Worqlul, A., Abu Hammour, D., Hilali, M. E.-D., and Gazal, O.: Watershed Resilience - Soil and Water Management in Arid Regions to Prevent Desertification, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18000, https://doi.org/10.5194/egusphere-egu24-18000, 2024.

Agricultural management behavior is one of the core features of agricultural soil ecosystems. Poor human management may contribute to the rapid degradation of soils on a world-wide scale.Traditional management, which usually aims to maximize productivity, faces great challenges when pursuing agricultural soil health, high efficiency, and sustainable development. Evaluating the agricultural soil management system based on multiple perspectives is crucial for effectively guiding the management framework. A large number of research on agricultural management evaluation mainly focues on national and regional scales, and the evaluations are dominated by socio-economic indicators. Comprehensive evaluations at the sample scale, that incorporate specific agricultural management techniques need to be further explored.This paper establishes an agricultural management evaluation system at sample-scale based on the DSR logical framework. The capital- and labor-related indicators are used as system Drivers, technical indicators resulted from soil management and soil properties to characterize the management Status, and economic output-related indicators as system Responses. Then, a comprehensive index is calculated to inform the economic characteristics, ecological friendliness, and soil health status. As the case study, three distinct agricultural soil management systems of apple orchards in Chinese Luochuan were assessed. The results show that organic-management system is superior for excellent management skills, the conventional management system is lowest in the index due to inferior drivers and technical indicators. The green- management system is middle one. The method is useful for evaluating the soil management system in the similar agricultural areas in the world.

How to cite: sun, W., zhang, X., Gomez, J. A., Bai, G., An, Z., and Liu, X.: Evaluating agricultural management systems: Case study of apple orchards in Chinese Luochuan, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8651, https://doi.org/10.5194/egusphere-egu24-8651, 2024.

Agricultural intensification has used technological advances to raise food production, but it has also created environmental imbalances. Environmental degradation, e.g. soil loss and offsite contamination, and loss of biodiversity, related to the expansion and intensification of agriculture, have been documented internationally^[1][2]. Since the 1980s, with the Single European Act^[3] as a legal basis, different attempts have been made to address this threat at European level through better focused environmental policies. For instance since the CAP reform in 1992, environmental sustainability of agriculture has been constantly ongoing. In fact, the latest reform post-2021 shows more ambitious objectives with the introduction of eco-regimes. Other key initiatives like the Green Infrastructure Strategies and the EU Mission: A Soil Deal for Europe have emerged^[4][5][6] being focused on recovering natural capital as a source of ecosystem services.

In this context, ALIve^[7], SCALE^[8] and ECOMED^[9] projects and the Rural Landscape Diversification Program of the Córdoba Countryside^[10] aim to provide scientific and technical knowledge for the sustainable intensification of agriculture in Mediterranean areas, in particular southern Spain, through nature-based solutions.

Although vegetative barriers are one of the key instruments to manage agricultural landscapes towards sustainable intensification, detailed empirical information on how to implement them still scarce. This communication presents an experiment on different alternatives on how to stablish a vegetative barrier combining fifty-two herbaceous and woody species adapted for Mediterranean conditions. This experiment explores seventeen different strategies, combining different irrigation, mulching and tillage combinations. In these plots, growth, survival and phytosanitary status of the plants, and soil moisture at the end of each hydrological year were monitored since its implantation in February 2021. This communication presents results from the first year of implementation, as well as a costs analysis of the different strategies evaluated. This information can be valuable for practitioners and planners interested in these nature-based solutions.

After the first year, it was observed that all the treatments presented a remarkable survival rate, above 48% (CoT4), albeit this increases with better management reaching 100% with better tillage, mulching and drip irrigation. Plant growth also responded to best management ranging from 14.1 cm in height (CoT4) and 11.8 cm in diameter (CoT3) to 46.7 cm in height (CoT9) and 58.8 cm in diameter (CoT9). The cost of implementation ranged from 1.7 €/m² (CoT4) to 6.0 €/m² (CoT9). Among the most successful individual operations is mulching with a fabric film, which despite having the highest implementation cost 2.5 €/m² results in the lowest maintenance cost 0.4 €/m².

Acknowledgements: ALIve (PID2019-105793RB-I00), SCALE (Nº 862695) and ECOMED (PR.AVA23.INV202301.035).

References:

[1] MITECO, «Plan estratégico estatal del patrimonio natural y de la biodiversidad a 2030». 2022.
[2] European Commission, «EU Biodiversity Strategy for 2030». 2020.
[3] European Economic Community, «Single European Act». 1987.
[4] European Commission, «Green Infrastructure (GI) — Enhancing Europe’s Natural Capital». 2013.
[5] MITECO, «Estrategia Nacional de Infraestructura Verde y de la Conectividad y Restauración Ecológicas». 2021.
[6] European Commission, «EU Mission: A Soil Deal for Europe». 2023.
[7] https://alive.csic.es/
[8] https://ejpsoil.eu/soil-research/scale/
[9] https://www.juntadeandalucia.es/agriculturaypesca/ifapa/web/node/60947
[10] https://www.jardinbotanicodecordoba.com/investigacion/diversificacion-del-paisaje-agrario/

How to cite: Montoliu, J., Guzmán, G., Lora, Á., Mora, J., Soriano, M. A., and Gómez, J. A.: Vegetative barriers as a nature-based solution for agricultural landscapes diversification: design and management of this green infrastructure in a Mediterranean climate., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3052, https://doi.org/10.5194/egusphere-egu24-3052, 2024.

Vineyards are often located in areas with poor soil quality and hilly terrain. Conservation agricultural management with the inclusion of cover crops helps to maintain or increase the existing soil fertility in these areas that are difficult to cultivate. However, there are also several reasons in favour of keeping vineyard inter-rows bare, including competition for water and nutrients, restrictions in pest control, and additional costs. As a result, a variety of site-adapted inter-row management systems have been developed in the different wine-growing regions. We investigated the effects of common management practices on soil organic carbon and soil physical parameters in topsoils of Austrian, French, Romanian, and Spanish wine-growing regions. In each region, we analysed management systems with and without cover crops. The comparison between the vineyard regions shows the variety of management intensities across the vineyard regions and their effects on soil quality parameters. Due to the differences in climate, soil, and management systems and, in particular, the mechanical soil disturbance intensity, bare soil, and cover crop management led to a broad range of soil organic carbon stocks, soil structure parameters, and soil hydraulic properties. While cover crop management caused an increase in carbon stocks in most vineyards compared to bare soil management, cover crop management in Spain was not effective in increasing soil organic carbon accumulation. In line with the increase in organic carbon also the measured soil structure parameters improved, yet the extent depended on the type and intensity of soil disturbance. The least clear effects of inter-row management systems were found for soil hydraulic parameters. As the local management strategies are a combination of adaptations to local conditions, farmers' experiences, and historical developments, the findings from the comparison of the systems can be used to rethink local strategies and improve the individual systems. This primarily concerns the type and intensity of cover crop management.

How to cite: Strauss, P., Strohmeier, S., Toth, M., and Liebhard, G. C.: Effects of common inter-row management practices on vineyard soils in four European vineyard regions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6470, https://doi.org/10.5194/egusphere-egu24-6470, 2024.

Biochar application to agricultural soils represents a strategy for carbon sequestration and soil quality enhancement. However, long-term field studies on the interactive effects of combined application of biochar and inorganic or organic fertilizers on temperature sensitivity of soil respiration (Q₁₀) are still scarce. To address this gap, a long-term field experiment with a randomized block design was established in a semiarid agricultural soil in Central Spain in 2012. The treatments used for this study included unamended control, amendment with biochar (B) at a rate of 20 t ha^-1 year^-1, mineral fertilizer (MF), municipal compost (MC) and sewage sludge (SS) at rates to meet N crop demands and the co-amended B+MF, B+MC and B+SS applied at the same application rates used for the individual treatments. Soil samples were taken post-harvest of 2023, eight months after the latest soil amendments. A series of soil incubations were set to a range of 5-35 °C for CO₂ measurements, which were addressed using the fully automated system Respicond respirometer X. Overall, Q₁₀ values were not affected by the co-application of biochar and fertilizers. Only soils amended with MC showed a significant increase in the Q₁₀ value in comparison to the B, MF and unamended control treatments. Furthermore, MC-amended soils showed higher respiration rates than those amended with SS. This difference could be attributed to the rapid mineralization of labile carbon fractions added with SS in preceding months or to the presence of preserved complex substrates in MC treatments that could decompose over the long-term. It could also be linked to a higher accumulation of SOC over the past 12 years in MC-treated soils compared to those treated with SS, thereby influencing the observed variations in respiration rates. On the other hand, co-application of biochar with fertilizers decreased soil CO₂ fluxes, especially for B+MC and B+SS, in comparison to the treatments applied alone. The study suggests that in semiarid soils the combined application of biochar with other fertilizers may induce beneficial synergistic effects, creating a nutrient-rich soil environment while either limiting soil CO₂ fluxes and mitigating the adverse impact on the temperature sensitivity of carbon mineralization. 

Acknowledgments: This research was supported by the Ministry of Science and Innovation (“BIOGEOCHAR” Project grant ref. TED2021-132342B-I00). M.J.C thanks to the Embassy of France in Spain for supporting her postdoctoral stay in the Biogéosciences Unit and MINECO for her “Juan de la Cierva-Formación” postdoctoral contract.

How to cite: Carpio Espinosa, M. J., Bonnefoy-Claudet, C., Thévenot, M., Mathieu, O., Benavente-Ferraces, I., García-Gil, J. C., Plaza, C., and Panettieri, M.: Effects of biochar and its co-application with inorganic and organic fertilizers on soil microbial respiration and temperature sensitivity of carbon mineralization., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2795, https://doi.org/10.5194/egusphere-egu24-2795, 2024.

Leaf functional traits (LFTs) can directly or indirectly reflect the adaptation strategy of plants to the environment, influencing their survival, growth, and reproduction. However, there is still uncertainty as to the relationship between LFTs and environmental gradients, especially in resource-limited regions. In this study, we selected Artemisia ordosica communities as the research objects at four different dune fixation stages, including semi-fixed (D1), fixed (D2), soil-crust fixed (D3) and herbaceous-plant-covered fixed sand dunes (D4) in Mu Us Desert. Based on field investigation and laboratory analysis, we examined the characteristics of 13 LFTs and the relationship between of LFTs trade-offs and soil physicochemical environment under different dune fixation stages. It was found that (1) in community level, leaf area (LA) and specific leaf area (SLA) were the largest at D1, while leaf tissue density (LTD) and leaf dry matter content (LDMC) shown gradually increasing trend with dune fixation. The results indicated that plants will adapt to progressively increasing competition by reducing their photosynthetic capacity and enhancing their physical defense structures. (2) with ongoing dune fixation, the soil organic carbon content (SOC) and soil total nitrogen content (STN) were significantly higher in D2-D4 than that in D1, and soil water content (SWC) was the highest in D2, then decreased significantly in D3-D4 with increasing community species. (3) according to the results of redundancy analysis (RDA), the two main axes represented the soil physical condition (54.11%) and chemical condition (30.06%), respectively. And the SWC and SOC were the main factors affecting changes in LFTs during the dune fixation. Our results provide theoretical basis for understanding the resource use strategy and adaptation mechanism of desert plants under stress environments.

How to cite: Tian, Y., Dai, Y., Xu, M., Zhou, Y., Ju, X., Zha, T., Jia, X., and Liu, P.: Responses of leaf functional traits to soil environment at different sand fixation stages in the Mu Us desertland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4934, https://doi.org/10.5194/egusphere-egu24-4934, 2024.

Potatoes are especially susceptible to erosion when grown on long and sloped fields due to late seed development and the unique structure of their seedbed. Previous research has shown that micro-dams can effectively reduce surface runoff and sediment yield while also increasing soil water content. One way to further improve micro-dams is to cover them with a greening crop, such as oat or wheat. During intense precipitation events, micro-dams may break and lose their protective effects, whereas micro-dams with cover crops are more sustainable and stay intact. Therefore, this study aims to analyze the resilience of both micro-dams and micro-dams with cover crops on selected fields and all Austrian potato fields in 2022 to intense rainfall events.

Between 2019 and 2022, seven potato fields with both micro-dams and covered micro-dams were surveyed using UAVs (Unmanned Aerial Vehicles) to collect elevation data. This data was used to create digital elevation models (DEM), which were then utilized to evaluate the state of each micro-dam on the field, i.e., whether it was intact, damaged, broken, or undefinable, as well as to calculate topographic parameters, such as slope and LS-Factor, for each micro-dam's position. After a specific precipitation event, the state of each micro-dam was compared with its respective slope and LS-Factor. The obtained data was subsequently applied to all Austrian potato fields of 2022 to assess the potential of micro-dams and micro-dams with cover crops to withstand intense precipitation events and their potential effectiveness.

The first results indicate that there is a distinct difference in slope and LS-Factor between stable and broken micro-dams, regardless of whether they are covered with a greening crop or not. The median slope of all broken micro-dams, whether covered or uncovered, is 8.4%, while stable micro-dams are situated at a median slope of 6%. A similar ratio can be observed in the LS-Factor, with a median of 1.75 for broken micro-dams and 1.15 for stable micro-dams. There are differences between uncovered and covered micro-dams regarding their slope or LS-Factor in all possible states for micro-dams, yet these differences are small and not significant. The application of the data to all potato fields in Austria in 2022 is still ongoing.

How to cite: Konzett, M., Strauss, P., and Schmaltz, E.: Unraveling the resilience of micro-dams on Austrian potato fields during intense rainfall , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5554, https://doi.org/10.5194/egusphere-egu24-5554, 2024.

Societal and agronomic changes during Tajikistan’s post-soviet era have altered the rural farmland management and the related catchment hydrology. The increasing demand for food production and the limited crop diversity eventually affected soil health and surface hydrological processes. Late planting of summer crops, the removal of plant residues and intense soil disturbance through ploughing are accompanied with limited rainfall interception, which fosters runoff and eventually erosion with potentially disastrous consequences in the downstream areas. As part of Caritas Switzerland's Weather, Water, Climate Services (WWCS) initiative, jointly funded with the Swiss Agency for Development and Cooperation, this study assesses the adoption of Sustainable Land Management (SLM) practices at the field level to reduce surface runoff and erosion, while diversifying and enhancing crop production. This study focuses on a 6356 km² large watershed in the Khatlon region of Tajikistan and couples field experimental runoff plot monitoring with process-based hillslope scale modeling (Water Erosion Prediction Project; WEPP), eventually connected with watershed level hydrological assessment (Soil and Water Assessment Tool; SWAT). Field experimental procedures are being conducted through national, international and local citizen scientists. The study is in its initial phase – however, one season of plot monitoring has been conducted that allows a preliminary assessment of the surface runoff and erosion response of bare, summer wheat, chickpea, alfalfa and esparcet plots. The experiment enables the assessment of the single crops’ performances, as well as integrating crops into rotations through modeling. At the same time, land use and land cover (LULC) ground truthing within the Khatlon watershed was undertaken to validate two freely available global data products provided by the European Space Agency ESA; the CCI LC 300m and the ESA WorldCover 10m datasets. From the ESA CCI LC product, a comprehensive time series from 1992 to 2020 was developed to analyse the changes in LULC within the research area. The validation process enhances the reliability of the LULC data, which is also important for modelling purposes, in the Khatlon region. In a next step, involving multiple stakeholders, land suitability assessment and mapping will yield plausible watershed management scenarios to evaluate the potential of diversification and the introduction of multi-seasonal crops (i.e. alfalfa and esparcet) to reduce surface runoff and sediment yields from the farmlands and to strengthen the local agro-ecosystems and their sustainable production.

How to cite: Konold, O., Benedek, C., Visintin, P., Thier, M., Stoisser, V., Stumpp, C., Mehdi-Schulz, B., Khudonazarov, F., Kassam, S., Aminov, S., Khojaev, D., Khojaev, S., Haddad, M., Akramkhanov, A., and Strohmeier, S.: From plot to catchment scale: evaluating historical and adapted land management practices in an agricultural watershed in Tajikistan, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17404, https://doi.org/10.5194/egusphere-egu24-17404, 2024.

How to cite: Dai, H., Wang, R., Chen, L., Wang, L., Wang, X., Xiong, C., and Zhang, M.: Effects of Different Micro-Irrigation Methods on Water Use and the Economic Benefits of an Apple–Soybean Intercropping System, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2434, https://doi.org/10.5194/egusphere-egu24-2434, 2024.

    Soil erosion is one of the most widespread and serious environmental problems globally. Accurately obtaining understory vegetation parameters is a challenge for regional soil erosion assessment. This article introduces a method for obtaining understory vegetation Leaf Area Index (LAI) using multi-angle remote sensing techniques. Based on the Moderate-resolution Imaging Spectroradiometer (MODIS) Bidirectional Reflectivity Distribution Function (BRDF) data product (MCD43A1), the 4-scale geometric optical model was used to separate forest canopy and background reflectance. Combined with the measured understory LAI, a model for the inversion of understory LAI in the study area was developed. The results demonstrated that the background reflectance showed a similar seasonal variation trend as the reflectance of adjacent grassland, and significant difference was found between the background reflectance and the corresponding pixel total reflectance. Total reflectance was fitted separately with the measured canopy LAI and understory LAI. The coefficient of determination, R-square value between total reflectance and measured canopy LAI was 0.419, while the R-square value between total reflectance and measured understory LAI was only 0.053, it was indicated that the total reflectance mainly represents the information of the canopy. Established simple inverse models for the leaf area index of understory vegetation. the correlation between understory vegetation LAI and Ratio Vegetation Index (RVI) calculated based on background reflectance was the best, with the R-square value of 0.4733, Root Mean Square Error (RMSE) of 0.55, and Mean Relative Error(MRE) of 14.62%. This research can provide a method for evaluating understory vegetation in the quantitative estimate of regional soil erosion.

KeyWords：Leaf area index; Multi-angle remote sensing; Background reflectance; Understory vegetation.

How to cite: Wang, H., Zhang, X., He, L., Geng, W., and Sun, W.: Preliminary exploration of understory leaf area index inversion based on multi-angle remote sensing., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8732, https://doi.org/10.5194/egusphere-egu24-8732, 2024.

Estimation and evaluation of carbon sink of terraces measures in Loess Plateau : A Case Study of Wuqi County

Kaiyang Yu¹, Xiaoping Zhang¹, Hui Cheng², Weinan Sun¹, Wenliang Geng¹, Haojia Wang¹, Xuanhao Liu¹, Liang He¹, Yujie Zhang¹, Zefeng An¹, Yichen Wang¹

¹Institute of Soil and Water Conservation, Northwest A&F University, Yangling, Shaanxi 712100, China

²Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, Shaanxi 712100, China

Abstract: Extensive terracing to cultivate land or plant trees and grasses, will affect biogeochemical processes in terrestrial ecosystem especially in areas with severe erosion. In order to clarify the carbon sequestration function and capacity of terrace in Loess Plateau, terraced fields with different planting types and years were selected to compare with corresponding slope land within Wuqi County (3,791 km²) of Loess Plateau to investigate the distribution characteristics of SOC on soil profile in 100 cm and searching for the influencing factors in the area. The results showed that：(1) Level terrace has significant carbon sink function in Loess Plateau. After the construction of terraced fields, SOC of six soil layers has the same variation trend with the construction years. The total SOC in the profile undergoes a rapid accumulation in the early 5-10 years of terracing construction, then exceeded the control group, and reaching a stable level after 20 years. (2) SOC in terrace dramatically decreases from surface layer to bottom layer, which exhibits surface aggregation effects. The content of SOC in 0-10 cm is significantly higher than that in deep soil layers, and the difference in SOC in deep soil is not significant. (3) The contents and accumulation rate of SOC in terrace are different with the planting types and years. Terraces with forest land generally has higher accumulating rate than other planting types. (4) There is significant correlation between total SOC and organic carbon content of large soil aggregates. Soil aggregates with particle size greater than 0.25mm determined the amount and trend of SOC content in the soil.  These results can provide an essential basis for improving the soil fertility and evaluating the benefit of terrace in carbon conservation on the Loess Plateau.

Key words: Terrace; Soil organic carbon; Soil aggregate; Loess Plateau

How to cite: Yu, K., Zhang, X., Cheng, H., Sun, W., Geng, W., Wang, H., Liu, X., He, L., Zhang, Y., An, Z., and Wang, Y.: Estimation and evaluation of carbon sink of terraces measures in Loess Plateau : A Case Study of Wuqi County, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9522, https://doi.org/10.5194/egusphere-egu24-9522, 2024.

Abstract: As the fundamental foundation for human survival and development, the ecological environment is an important guarantee for social progress. With the accelerated development of society, the impact of human activities on the ecological environment has become increasingly significant. Fu County (4,182 km²) is located in the gully area of the Loess Plateau, an important ecological security barrier in the north of China. Clarifying the current situation of the ecological environment and the temporal and spatial changes of ecological environment quality in Fu County is conducive to the construction of ecological civilization. It provides scientific support to improve ecological quality.

Based on the remote sensing images of Landsat in Fu County from 1992 to 2019, we considered four indexes of Normalized Difference Vegetation Index (NDVI), Tasseled Cap Transformation Humidity Index (Wet), Normalized Difference Bare Soil Index (NDBSI), and Land Surface Temperature (LST) to represent greenness, humidity, dryness and heat of the environment. The principal component analysis was uesd to establish a remote sensing ecological index model (RSEI). And then we evaluated the ecological quality in the area in the past 30 years.The results showed that: (1) The average correlation between RSEI and four indexes was 0.874, which means RSEI can comprehensively reflect the ecological environment quality status of the study area compared with a single index. (2) The regional mean values of RSEI in Fu County showed an upward trend from 0.621 to 0.806 between 1992 and 2019, and the increase in ecological environment quality gradually increased from northwest to southeast of the county. (3) The increasing area and magnitude of the ecological level of the county from 1992 to 2019 were much greater than the decling area and magnitude. Over the past 30 years, the relatively sparsely populated townships of Zhiluo, Niwu and Zhangjiawan, which have a high degree of vegetation cover, have always been in a better state, while the densely populated townships of Jizixian, Jiaodao and Yangquan has always been poor. From the perspective of the degree of change in the quality level of the ecological environment, all townships have been improved to different degrees, and the improvement is the most obvious in Jizixian Town, Jiaodao Town and Yangquan Town.

The improvement of ecological environment quality level from good to excellent is probably because that the implementation of many ecological projects and the increase in rainfall, and the decrease in bare soil area and surface heat decreased in Fu County in the past 30 years.This study can provide method reference and data support for ecological environment monitoring, governance and protection.

Keywords: Fu County; Ecological environment quality evaluation; RSEI; Dynamic monitoring

How to cite: Zhang, Y., Zhang, X., He, J., He, L., Sun, W., Geng, W., Wang, H., Wang, Y., An, Z., Yu, K., and Liu, X.: Ecological environment quality evaluation of the gully area in the Loess Plateau based on remote sensing ecological index, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7421, https://doi.org/10.5194/egusphere-egu24-7421, 2024.

Uneven soil moisture and nutrient distribution before and after intercropping limits apple cropping system productivity in the western Shanxi loess area. To address the problem, a field experiment was conducted between 2020 and 2021 to investigate the effects of different water and fertilizer management practices on soil moisture, nutrients, root distribution, and overall benefits of the intercropping system during the crop replacement period. The experimental set up included three factors: irrigation method, irrigation level, and fertilizer application; irrigation methods included drip (D) and flood (M) irrigation; irrigation levels included rain-fed without irrigation (W0), 50% of the field water holding capacity (Fc)-W1, and 80% of the field water holding capacity (Fc)-W2; fertilizer treatments included F0 (no additional fertilizer application), F1 (N 206.2 kg∙hm^-2 + P₂O₅ 84.4 kg∙hm^-2 + K₂O 84.4 kg∙hm^-2), F2 (N 412.4 kg∙hm^-2 + P₂O₅ 168.8 kg∙hm^-2 + K₂O 168.8 kg∙hm^-2), and control (CK) without irrigation and fertilization, for a total of 15 treatments. According to the results, soil water content (SWC) decreased after the crop replacement. Besides, nitrate nitrogen (NN), ammonium nitrogen (AN), and organic matter (OM) contents in all treatments increased, whereas total phosphorus (TP) content decreased. The main soil aggregate layer with crop roots shifted downwards (from the 0–40 cm soil layer before crop replacement to the 0–60 cm soil layer) after crop replacement, and partial fertilizer productivity (PFP), irrigation water use efficiency (IWUE), and water use efficiency (WUE) under both irrigation treatments were decreased. Principal component analysis showed that the W2F2 treatment had the highest combined benefits both irrigation treatments during the crop replacement period. Structural equation modeling showed that apple tree and maize RLDs had no significant effects on water use (ET) and WUE before crop replacement. Apple tree and soybean RLDs had significant positive correlations with ET and significant negative correlations with WUE after crop replacement. According to our results, to optimize the benefits of apple-crop intercropping, drip irrigation with complete water supply and flood irrigation with incomplete water supply are recommended during crop replacement. In addition, an upper irrigation limit of 80% of the field water holding capacity and a fertilizer application rate of N 412.4 kg∙hm^-2 + P₂O₅ 168.8 kg∙hm^-2 + K₂O 168.8 kg∙hm^-2 are recommended for optimal water and fertilizer regulation.

How to cite: Xiong, C., Wang, R., Wang, X., Wang, L., Chen, L., Dai, H., and Zhang, M.: Soil Moisture, Nutrients, Root Distribution, and Crop Combination Benefits at Different Water and Fertilizer Levels during the Crop Replacement Period in an Apple Intercropping System, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2503, https://doi.org/10.5194/egusphere-egu24-2503, 2024.

Abstract: Mulching and supplementary irrigation are commonly used water-saving techniques ensuring agricultural sustainability in drylands of northwest China. However, the effects of the combination of mulching and supplementary irrigation on the soil environment, and the growth of apple trees remain unclear. Field experiments were conducted in 2023 to evaluate the effects of the combination of mulching and supplementary irrigation on the soil water and heat, and the growth of apple trees. In the experiments, one mulching method (corn straw mulching, SM), two types of drip irrigation, which included above-ground ring drip irrigation (M1) and above-ground two-row drip irrigation (M2), were used. Additionally, three irrigation levels of 100% (W1), 75% (W2), and 50% (W3) of full irrigation (referred to as full, moderate deficit, and severe deficit irrigation, respectively) were used. The results showed that SM significantly increased the soil water content (SWC), especially in the early stage of the growth period. SM significantly reduced and stabilized the soil temperature during the whole growth season, while M1 and M2 had no significant effect on the soil temperature. Both mulching and drip irrigation significantly increased the net photosynthetic rate (Pn) of leaves. Supplementary irrigation had no significant effect on shoot length, but increased shoot diameter. The evapotranspiration of various stages on apple trees was in the following descending order: fruit expansion stage (III), bud development and flowering stage (I), leaf expansion stage (II), and fruit maturing stage (IV). Therefore, SM has the potential to increase apple yields in the Loess Plateau by improving the soil environment and regulating the growth and physiology of apple trees.

How to cite: Yang, Y.: Integrating mulching and supplementary irrigation for soil environment improvements in apple orchards of northwest China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3768, https://doi.org/10.5194/egusphere-egu24-3768, 2024.

     Vegetation phenology is widely recognized as a comprehensive indicator of global climate change. Studying the spatiotemporal characteristics and trends of regional vegetation phenology can improve our understanding of the stability and dynamic changes of the ecosystem. Based on the 16day, 250m resolution MODIS NDVI data from 2001 to 2020, this study used the S-G filtering method and the relative threshold method to extract vegetation phenology parameters in the Yellow River Basin. Combined with the ERA5-LAND hourly climate reanalysis dataset and CHIRPS daily precipitation dataset provided by GEE platform, using trend analysis and partial correlation analysis methods, we explored the spatial distribution characteristics and change trends of vegetation phenology in different vegetation zones under global climate change.We also analyzed its response to climate factors.The results show that: (1) the climate in the Yellow River Basin presented a warm and humid development trend from 2001 to 2020, with an annually average temperature increase of 0.15℃/10a (P>0.05) and an annual precipitation increase of 24mm/10a (P<0.05). (2) The warm temperate deciduous broad-leaved forest region in the Yellow River Basin had the earliest start of the growing season and middle time of the season, while the typical grassland subzone in the southern temperate zone and the desert grassland subzone in the southern temperate zone had the latest start of the growing season and middle time of the season. The end of the growing season in the temperate shrub-grass semi-desert zone was the latest, and the length of growing season in the alpine vegetation region on the Qinghai-Tibet Plateau was the shortest. (3) Within the whole basin, 69.3% and 66.4% of the area showed an advance trend (P<0.05) for start of the growing season and middle time of the season, respectively, 50.9% of the area showed a delay trend (P<0.05) for end of the growing season, and 66.1% of the area showed an extension trend (P<0.05) for length of growing season. (4) There were differences in climate impacts on phenology parameters among different vegetation zones. Temperature had a greater impact on phenology parameters in typical grassland subzone in northern temperate zone, alpine grassland zone, and alpine meadow zone, while precipitation and solar radiation factors had a greater impact on phenology parameters in typical grassland subzone in southern temperate zone, temperate shrub-grass semi-desert zone, desert grassland subzone in southern temperate zone and mid-subtropical evergreen broad-leaved forest zone.

How to cite: yichen, W., jie, H., liang, H., yujie, Z., and xiaoping, Z.: Vegetation phenology and its response to climate change in the Yellow RiverBasin from 2001 to 2020, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3716, https://doi.org/10.5194/egusphere-egu24-3716, 2024.

To explore the soil water holding capacity and soil structure on sloping farmland with terrace measures in Black Soil Region of Northeast China. The construction of terraces slope farmland in different soil types (Black soil, Dark brown soil and Brown soil) is taken as the research object, the slope farmland (non- terraced slopes) was used as a blank control (CK). In the study, the spatial uniform distribution method was used to quantify the soil water holding capacity, soil structure characteristics and spatial distribution characteristics of construction of terraced slope farmland. The results showed that (i) the physical properties of soil after terrace construction in Black Soil Region were better than that of CK, and the improvement degree was Brown soil > Black soil > Dark brown soil. (ii) Compared with the CK, the soil physical properties of Brown soil in terrace slope farmland were improved obviously. The soil saturated water holding capacity of terrace slope farmland increased by 10.24 %. Besides, the soil capillary water holding capacity of terrace slope farmland increased by 16.77 %, and the soil field water holding capacity of terrace slope farmland increased by 16.10 %. Compared with the CK, the soil structure characteristics of Brown soil in terrace slope farmland were also more stable, and he total soil porosity and capillary porosity of terraced slope farmland increased by 9.14 % and 15.56 %. (iii) Terraced slope farmland of Brown soil mainly affect soil moisture characteristics and soil porpsity, in which soil capillary water holding capacity with 12.11 % of contribution rate, and the contribution of terraces to total soil porosity was 11.21 %. The main influencing factors of terraces in Dark brown soil were soil structure characteristics, in which the contribution of soil total porosity was 13.84 %, and the contribution of water-stable aggregate content was 13.31 %, which were greater than that of CK ; The contribution rate of each index of terrace of Black soil is relatively uniform, at 10.24 % -12.5 %. In summary, the terraces of Brown soil affect the characteristics of soil moisture and soil structure. The terraces of Dark brown soil mainly affects the characteristics of soil structure. Terraces of Black soil mainly affect soil moisture characteristics.

Keywords : black soil region; terraces; soil water holding capacity ; characteristics of soil structure ;

How to cite: Wei, S. and Fu, Y.: Study on Soil Physical Properties of Terraced Slope Farmland in Black Soil Region of Northeast China., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13812, https://doi.org/10.5194/egusphere-egu24-13812, 2024.

The total area of soil degradation in China is about 460 million hectares, and the problem of soil degradation needs to be solved urgently. Can government regulation, as an important means to encourage farmers to use soil remediation technology, and guide farmers to improve their awareness and thus promoting their adoption? Based on the survey data of 403 rural households in Shaanxi and Shanxi provinces of China, the orderly probit model was used to empirically analyze the direct effects of government regulations on various soil remediation behaviors of rural households. Factor analysis was used to measure the cognition level of policy effectiveness, ecological benefit, social value and subject responsibility, and their effect on the government regulation is analyzed through the intermediary effect model. It was found that farmers in loess area had good soil remediation behavior and adopted 3 remediation techniques on average. The influence of different government regulations on farmers' soil remediation behavior is heterogeneous. Government subsidies and technical training significantly promoted farmers to implement soil remediation behavior, while publicity and education had no significance and negative impact. Further mechanism test showed that policy cognition and subject responsibility cognition played a positive moderating role, while social value cognition and ecological benefit cognition played a negative masking effect. The influence of propaganda and training on farmers' soil remediation behavior was 42.69% and 32.73% through social value cognition by masking effect. Therefore, it was necessary to put more allowances, carry out in-depth and meticulous publicity and education, broaden technical guidance channels, and adhere to the combination of rewards and punishments, to promote farmers' scientific soil testing and precision fertilization, and improve the agricultural green development mechanism.

How to cite: Li, S. and Liu, J.: How Does the Government Regulation Affect Farmers’ Soil Remediation Behavior?—Based on a Mediation Effect Analysis of Farmers’ Cognition, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14064, https://doi.org/10.5194/egusphere-egu24-14064, 2024.